Slightly OT: The other warnings shown in monkey_boy's example of running your code with warnings enabled, the ones about "main::printme() called too early to check prototype...", can be silenced by either declaring or defining the prototyped subroutine before the subroutine is ever invoked:

c:\@Work\Perl\monks>perl -wMstrict -le
"sub printme();
 ;;
 my $x = 'a';
 printme();
 ;;
 $x = 'b';
 printme();
 ;;
 sub printme () {
   print qq{x: '$x'};
   }
"
x: 'a'
x: 'b'
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Or better yet: Just don't use Prototypes. See Far More than Everything You've Ever Wanted to Know about Prototypes in Perl -- by Tom Christiansen.